FIG. 1 shows a typical reverse osmosis (RO) water filtering system 10 constructed in accordance with the prior art. The filtering system 10 is designed to work in parallel with a traditional system. The traditional system has a standard water faucet 62 fed by hot and cold water sources 82, 84 through angle stop valves 56, 36, respectively. The faucet 62 dispenses water above a standard sink drain 68 that can be shared with the system 10.
The system 10 includes a filter assembly 14, a reverse osmosis membrane 18, a reverse osmosis storage tank 22, a flow restrictor 26, a shut-off valve 28, a carbon filter 70 and an auxiliary faucet 72. The filter assembly 14 includes a sediment filter 30 and carbon filters 34a, 34b. Intake water enters the system 10 from a cold-water angle stop valve 36, which is connected to a cold-water source 84, and is routed through an intake tube 38 to filter assembly 14.
The sediment filter 30 removes sediment such as sand and dirt and the like from the intake water, while the carbon filters 34a and 34b remove chlorine and other contaminants that cause bad color, odor and taste. The filtered water is then routed to the membrane 18 through a water tube 40. The membrane 18 includes three ports: an intake port 42, a permeate outlet port 46, and a concentrate outlet port 50. The intake port 42 receives filtered intake water from the filter assembly 14 through the water tube 40. The permeate water is routed from outlet port 46 through permeate tubes 52a and 52b and shut-off valve 28 to tank 22 to be stored under pressure. The shut-off valve 28 is automatic and stops the flow of water to the membrane 18 and to the tank 22 when the tank is full. As a result, filtered water is not wasted by constantly flowing.
When the auxiliary faucet 72 is opened by a user, permeate water is forced from the tank 22, through a carbon filter 70, and though the faucet 72. Concentrate water is routed from the outlet port 50 through a wastewater tube 78 through a drain tube 74 for subsequent disposal down drain 68. Including a flow restrictor 26 in the wastewater tube 78 can reduce the flow of concentrate water to the drain 68.
Since water shortages are a problem in many arid and highly populated regions of the world, such as southern California, it is preferable that the concentrate water not be routed to the drain 68 in order to conserve water. Reverse osmosis systems that do not route the concentrate to the drain are referred to as “zero waste” reverse osmosis systems. For a common household reverse osmosis system, it has been suggested that the concentrate water can be discharged into the hot water line of the home for reuse instead of being routed to the drain. Because domestic hot water is not normally used for drinking, the presence of the concentrate water in the hot water line is acceptable.
In view of the above, additional zero waste reverse osmosis systems have been developed such as shown in FIG. 2 and referred to generally by the reference numeral 110. The system 110 of FIG. 2 is similar to the system 10 of FIG. 1 such that similar elements have the same reference numerals. In the system 110, however, the concentrate water is routed to a valve on the hot water angle stop 66 through tube 80 that has a flow restrictor 86 and two check valves 88a, 88b. The flow restrictor 86 is a larger rated flow restrictor than flow restrictor 26 of FIG. 1 in order to offset the backpressure from hot water source. The check valves 88a and 88b prevent hot water from the hot water source 82 from entering membrane 18 due to any backpressure that may occur.
The system 110 also includes an electric valve-pump assembly 90 between the membrane 18 and the filtering system 14. The electric valve-pump assembly 90 includes a solenoid valve 91, an electric pump 92, a pump intake tube 93, a valve-pump tube 94 that allows water to flow between the pump 92 and the solenoid valve 91, a valve outlet tube 95, a pressure switch 96 that is electrically connected to the pump 92 and the solenoid valve 91 by a wire harness 97, and a transformer 98 that supplies power to the pump 92, the switch 96, and the valve 91.
The transformer 98 is connected to an electric wall outlet (not shown). The pump intake tube 93 connects the filtering system 14 to the pump 92. The valve outlet tube 95 connects the solenoid valve 91 to inlet port of the membrane 18. The pressure switch 96 is connected between the permeate tubes 52a and 52b. 
In operation, the user opens reverse osmosis faucet 72 and the permeate water in the tank 22 is forced from the tank 22 by the pressure within the tank 22. As the tank 22 is being depleted of permeate water, the pressure switch 96 detects that the pressure within the tank 22 is below a predetermined pressure that corresponds to the tank 22 being filled. The pressure switch 96 then electrically opens the solenoid valve 91 and electrically engages the pump 92 to pump filtered water received from the filtering system 14 through the open solenoid valve 91 through the outlet valve tube 95 to the membrane 18.
The pump 92 continues pumping filtered water to the membrane 18 until the switch 96 detects that the pressure within tank 22 has reached a predetermined pressure, which corresponds to the tank 22 being full. The pump 92 also acts to provide enough system pressure to inject the concentrate water from the membrane 18 into the hot water line at 66. At the predetermined pressure, the switch 96 electrically disengages the pump 92 from pumping filtered water from the filter system 14 to the membrane 18 and closes solenoid valve 91.
In view of the systems above, additional systems have been developed. For example, see U.S. Published Patent Application No. 2007/0125710, published on Jun. 7, 2007, entitled “Non-electric zero waste reverse osmosis water filtering system.” Additional systems are shown in U.S. Pat. No. 5,045,197, issued on Sep. 3, 1991, entitled “Reverse osmosis purification system with unitary header manifold” and International Patent Cooperation Treaty Patent Application No. WO 2004/069368, published on Aug. 19, 2004, entitled “One-piece manifold for a reverse osmosis system.”